1. Field of the Invention
This present invention relates to a device for transferring objects, particularly for the loading or unloading of panes of glass.
The term "transfer" is understood to mean the operation consisting in gripping or picking up the object at a so-called gripping station and depositing it at a so-called depositing station.
"Loading" and "unloading" are understood to mean the transfer of the objects, in particular of plate elements or panes, from a gripping station to a depositing station, the objects (plates) passing from a substantially horizontal position at the gripping station to a substantially vertical position at the depositing station (so-called loading operation) or, inversely, from a substantially vertical position to a substantially horizontal position (unloading).
The device forming the subject matter of the invention was firstly created to solve the problem of loading and unloading panes of glass. In the production of flat glass, a continuous sheet or ribbon of glass emerges from the glass production unit (in accordance with the float glass process, for example), and the ribbon is then cut into individual panes. The sheet and the panes cut therefrom are carried by conveyors along a generally horizontal path, with the conveyor carring the sheet being known as the principal conveying lines. These panes are then stored on handling tracts or bucks provided with a desk or stand on which the panes are supported on edge in abutting vertical position. These panes may then be subsequently removed for further cutting to desired patterns.
The problem which is raised is that of transferring the panes from the horizontal cutting position to the vertical storage position, and vice versa.
2. Description of the Prior Art
Up to the present time, the problem of loading has been solved by means of devices of the type described in French Pat. No. 69 03391, corresponding to U.S. Pat. No. 3,679,0734. This device is composed of a system with conveyor rollers which transfer the pane from the end of the conveying line to the gripping station, and of a loading system which grips the horizontal pane and deposits it in vertical position on a desk. The loading system is designed with two parallel planes connected together by an articulated device incorporating two cross-pieces. The lower plane is constituted by two arms fixed to a shaft itself being adapted to be driven in rotation. The upper plane is constituted by two arms parallel to the lower arms and bearing suction cups.
Initially, the articulated system of the device is folded, the arms being disposed perpendicularly to the direction of displacement of the glass. The pane arriving at the end of the conveying line passes over the conveyer rollers which guide it to the gripping station, i.e. the pane abuts on the suction cups by two of its parallel sides. The arrival of the pane at the end of the gripping station acts on a contact placing the suction cups under depression. The system then tips so as to bring the pane into vertical position. Operation of the articulated system incorporating crosspieces allows the pane to be deposited at the spot designated.
Another device used heretofore is the one described in French Pat. No. 82 06604 for transferring a plate in vertical position towards a conveying line on which the plate will be in horizontal position. This operation is effected by means of a mobile gantry provided with a beam to which are fixed arms carrying suction cups at their ends. In this way, the plate is gripped on its truck in vertical position by means of the suction cups placed under depression. The gantry moves to bring the plate on a chassis pivoting in substantially inclined position. The chassis tips, and the plate is then in horizontal position and may be transferred onto the conveyor belt without difficulty. In order to increase the unloading rates, the Patent provides a rotation of 90.degree. of the beam bearing the arms, with the result that the arms in horizontal position do not hinder pivoting of the chassis, the operations of pivoting and return of the gantry into initial position then taking place simultaneously.
This state of the art reveals the necessity of a system of the pivoting support type for loading or unloading plates. The use of such a device leads to the question of its bulk in the workshop.
Until recently, the continuous sheet of glass leaving the production unit was cut across its entire width of about 140 inches (3.50 m) into a single pane 140 inches wide and of a predetermined length L, with the results that the positioning of one pivoting support at the end r at the side of the conveyer did not raise great difficulties. The panes thus stored on desks were transferred to cutting areas located outside the production unit for further cutting into panes of the desired length.
At the present time, in order to increase the rate of production of plates, the sheet of glass is directly cut out on the principal conveying line in both the longitudinal direction and in the transverse direction so as to obtain the panes of desired dimensions directly. In this way, several rows of panes advance on the conveying line, with the result that several panes arrive simultaneously at the gripping station.
It will be appreciated that the dimensions in length and in width of the loading devices in that case becomes a problem. The solution consists in spacing the loading devices and in using conveyor rollers of different lengths on each row in order to conduct the panes to the gripping stations (one station per row). Furthermore, the principal conveying line is located at about 51 inches (1.3 m) from the ground, which leaves too small a space in height for installing pivoting supports. Moveover, the devices used at the present time ensure in the best of cases rates of 4 second per cycle (per plate every 4 seconds), this still proving in practice to be insufficient.